<!DOCTYPE html>
<style>
.clamp {
  display: -webkit-box;
  -webkit-box-orient: vertical;
  -webkit-line-clamp: 5;
  font: 16px / 32px serif;
  background-color: yellow;
  overflow: hidden;
}
</style>
<div class="clamp">
  <div>
    Line 1<br>Line 2<br>Line 3<br>Line 4<br>Line 5<br>Line 6
  </div>
</div>
